Pluvial lake deposits in the Basin and Range province have long been exploited for records of hydrologic and climatic change. To obtain the most accurate reconstructions, a thorough understanding of the geomorphic evolution of such lake basins must be grounded in field stratigraphy and mapping, which are often lacking or are not well integrated with core studies. We conducted extensive stratigraphic investigation, mapping, and dating of exposed strata in the Lake Manix basin, former terminus of the Mojave River, California, during the Pleistocene to provide such a background and to supplement interpretations from a 45-m-long core.

In this paper, we emphasize the geomorphic and tectonic processes that shaped the evolution of the Manix basin after the arrival of the Mojave River in the early-middle Pleistocene. The main processes include (1) sedimentary infilling of the lake basin, (2) interaction among the subbasins as controlled by internal sills and sill failures, (3) tectonics, and (4) climate change. From about 500 to 190 ka, Lake Manix was confined to its western subbasins, and fluctuated in response to climate change and perhaps to brief diversions of the river into the upstream Harper Lake basin. During this time, about 24 m of sediment accumulated near the confluence of the Mojave River and Manix Wash, and a 15-km-long clastic wedge built into the western basins, gradually filling the accommodation space.

Two basin-integration events subsequently occurred, both caused by failure of sills that lay on sheared deposits along the Manix fault zone. When Lake Manix rose at the onset of glacial marine isotope stage 6, the sill on the south flank of Buwalda Ridge failed and triggered a catastrophic flood that entered the new, lower elevation, previously endorheic Afton subbasin. Subsequent lake-level changes affected both subbasins, but the thickest deposits after the flood are preserved in the Afton subbasin. The area upstream of Buwalda Ridge was only submerged during relatively high lake levels. Thus, sediment records interpreted from the core site and nearby outcrops in part reflect a geomorphic event (basin integration) rather than climatic conditions. The sill of Lake Manix after the integration event lay at the northeast end of the Afton subbasin, athwart strands of the Manix fault zone. At about 25 ka, this eastern sill was rapidly incised, and the river advanced to terminate in Lake Mojave in the Soda and Silver Lake basins. Recognition and dating of integration events, common for lake-river interactions in active tectonic settings, provide important context for interpreting paleoclimate records from sediments and provide temporal and spatial constraints on the biogeography of aquatic species.

长期以来，盆地和山脉省的湖泊沉积物一直被用于记录水文和气候变化。为了获得最准确的重建，必须以实地地层学和制图为基础，对此类湖盆的地貌演化有透彻的了解，而这些往往缺乏或没有与岩心研究很好地结合起来。我们对更新世期间加利福尼亚州莫哈韦河的前终点马尼克斯湖盆地的裸露地层进行了广泛的地层调查、制图和测年，以提供这样的背景并补充来自 45 米长岩心的解释。

在本文中，我们强调了在早中更新世莫哈韦河到达后塑造马尼克斯盆地演化的地貌和构造过程。主要过程包括（1）湖盆的沉积充填，（2）受内基台和基台破坏控制的子流域之间的相互作用，（3）构造作用和（4）气候变化。从大约 500 到 190 ka，马尼克斯湖被限制在其西部子流域，并随着气候变化而波动，也许是由于河流短暂改道到上游的哈珀湖流域。在此期间，莫哈韦河与马尼克斯河汇流处附近堆积了约 24 m 的沉积物，西部盆地中形成了 15 公里长的碎屑楔，逐渐填满了容纳空间。

随后发生了两次盆地整合事件，两者都是由沿着 Manix 断层带的剪切沉积物上的基石破坏造成的。当马尼克斯湖在冰川海洋同位素第 6 阶段开始上升时，布瓦尔达海岭南侧的窗台发生故障并引发了一场灾难性的洪水，洪水进入了新的低海拔、以前内陆的阿夫顿子盆地。随后的湖泊水位变化影响了两个子盆地，但洪水后最厚的沉积物保留在 Afton 子盆地。Buwalda Ridge 上游地区仅在湖水位相对较高时才被淹没。因此，从核心站点和附近露头解释的沉积物记录部分反映了地貌事件（盆地整合）而不是气候条件。整合事件后马尼克斯湖的基石位于 Afton 子盆地的东北端，横跨马尼克斯断层带。在大约 25 ka 时，这块东部的门槛被迅速切开，河流前进到苏达和银湖盆地的莫哈韦湖。整合事件的识别和测年，在活动构造环境中湖-河相互作用中很常见，为解释沉积物的古气候记录提供了重要的背景，并为水生物种的生物地理学提供了时间和空间限制。